Emission-line properties of the composite Seyfert/Starbust galaxy IC 5135

The galaxy IC 5135 is host to Seyfert activity and vigorous star formation in its nucleus. We present results of a study based on optical spectroscopy and imaging that reveal the ionization properties of the nucleus and near- nucleus region, as well as the global morphology of this galaxy. The dual nature of the nucleus is evident in emission-line profiles, which show two kinematic components. Line intensity ratios in the nucleus are typical of Seyfert 2 galaxies, but evolve with increasing radius to values generally characteristic of H II regions. IC 5135 provides an illustration of the importance of the [OI] λ 6300 line as a tracer of a hard-spectrum, photoionizing continuum; the presence at large radii of ionizing radiation from the nucleus is clearly revealed by the relative strength of this line. Possible distortions in the outer structure of this galaxy may have resulted from a recent dynamical encounter with a nearby companion.